1. Field of the Invention
The present invention relates to on-axle tire inflation systems, and more particularly to an on-axle tire inflation system utilizing an axle and oil cap assembly air distribution system for trucks and other vehicles.
2. Description of the Related Art
One problem associated with pneumatic tires, especially in tractor trailer systems, involves maintaining proper or appropriate tire air pressure. A low pressure situation in a tire can often go undetected for a long period of time. While it is prudent to periodically check tire inflation pressure with an air pressure gauge, such checks are sporadic at-best. A low pressure tire can cause many problems, as can, a high pressure tire.
The concept of providing an on-axle tire inflation system, or what is known as a central tire inflation system (CTIS) or automatic tire inflation system (ATIS), is well known in the art. Such systems remotely or automatically inflate a pneumatic tire rotatably mounted onto the axle of a vehicle via an air distribution system. Typically, an on-board source of pressurized air, such as compressed air from the vehicle air brake compressor and/or compressed air reservoir, is used to fill the tire and maintain tire pressure. In this manner, the pneumatic tire may be inflated without the need to remove the tire from the axle. Some systems may also provide for the deflation of the tire or air pressure monitoring.
Such on-axle tire inflation systems have been incorporated into many types of vehicles such as tractor-trailers and off-road vehicles. By incorporating such systems into the vehicle, tire pressure associated problems may be alleviated. These systems usually include a rotary union coupling air from a fixed member to a member rotating with the wheels. These rotary unions are key components and often subject to premature failure.
However, such prior art systems are generally complicated and/or cumbersome. Additionally, in the case of truck trailers, most truck trailers are provided with a lubrication compartment at the end of the axle for containing lubricant for the wheel bearings. Such systems may include an oil sight glass and an oil plug centered on the site glass for filling and inspecting the lubricant level in the lubrication compartment. A tire inflation system must therefore also incorporate or accommodate such a lubrication system.
Some prior art solutions also fixe critical components outside the hubcap thereby exposing these components making them susceptible to damage and requiring unnecessary maintenance and repair. An effective automatic tire inflation system reduces tire maintenance. However, it is counter productive to install an inflation system that creates additional maintenance and/or repair. There is desired an improved tire inflation system that has an improved rotary union, is easy to install and requires little maintenance.
The present invention achieves technical advantages as a tire inflation system having a rotary union seated and protected in a hollow axle, which system is easily mounted, and required little maintenance.
In a preferred embodiment thereof, the present invention is a tire inflation system for a vehicle having pneumatic tires mounted onto a hollow axle. The tire inflation system includes a source of compressed air, coupled to a hollow axle, an air interface device having a rotary union, and a oil cap assembly adapted to carry at least one tire. The air interface system is advantageously adapted to have the rotary union protected within the hollow axle to protect this key component from outside elements and failures, such as oil leaks and brake dust. A unique wedge mechanism secures the air interface system against the inner wall of the hollow axle, providing for quick installation and maintaining integrity.